1. Field of the Invention
This invention relates to valves. More particularly, it relates to sub plate mounted, pilot actuated spool valves.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
U.S. Pat. No. 5,771,931 to Watson discloses a reciprocating sleeve type valve mechanism having a valve housing within which is located a cage element. A piston, movably positioned within the valve housing, accomplishes linear opening movement of a cylindrical seal sleeve with respect to spaced polymer seals within the housing. Closing movement of the seal sleeve is accomplished by a return spring. Sealing between the cage element and a wear resistant external ceramic liner of the seal sleeve is accomplished by a seal assembly having a centrally located elastomer seal ring with polymer backup wiper rings positioned on opposite sides thereof. The seal assembly provides a bearing and guiding function to stabilize the seal sleeve during its opening and closing movement and to wipe particulate from the sealing surface of the seal sleeve as well as to maintain efficient sealing with the seal sleeve as the valve is opened and closed.
U.S. Pat. No. 4,887,643 to Tomlin et al. describes a housing that has a cage with supply fluid ports, vent ports and an outlet port. A pilot actuated hollow spool valve element is telescopically movable in the cage and engages poppet seats at opposite ends of the cage. Elongated supply and vent slots directed transversely to the axis of the cage and valve element provide maximum flow passages. The ends of the spool are in contact with the cage at all times and the axial extent of the contact between the spool and the cage is greater than fifty percent. The spool engages the interior of the cage at the fluid ports and vent ports for reducing flow restrictions. A recess coaxially positioned at each end of the cage receives one of the valve seats. The housing abuts the cage for properly loading the valve seats. A dash pot cushions the valve element. A pilot control stem is connected to the valve element exteriorly of the valve element. A seal carrier provides a seal between mating surfaces of an underwater control pod.
U.S. Pat. No. 4,457,489 to Gilmore describes subsea fluid conduit connections for remote controlled valves.
It has been found that the polymer seal plates in valves of this type tend to distort by bowing when subjected to higher pressures. The present invention solves this problem.